Air conditioning and heat pump systems for residential and commercial applications are known to employ modified automotive heat exchanger assemblies because of their high heat transfer efficiency, durability, and relatively ease of manufacturability. A typical automotive heat exchanger assembly includes an inlet manifold, an outlet manifold, and a plurality of extruded multi-port refrigerant tubes hydraulically connecting the inlet and outlet manifolds. The core of the heat exchanger assembly is defined by the plurality of refrigerant tubes and corrugated fins disposed between the refrigerant tubes for improved heat transfer efficiency and increased structural rigidity. For residential and commercial applications, the inlet and outlet manifolds typically extend horizontally while the refrigerant tubes extend vertically with respect to the direction of gravity.
The increased in scale of an automotive heat exchanger assembly for residential and commercial applications dramatically increases the lengths of the inlet and outlet manifolds, which may result in increased refrigerant mal-distribution through the core of the heat exchanger. For heat pump systems, in cooling mode the indoor heat exchanger assembly acts as an evaporator, and in heating mode the outdoor heat exchanger assembly acts as the evaporator. During operation in evaporative mode, a partially expanded two-phase refrigerant enters the lower portions of the refrigerant tubes from the inlet manifold, the lower manifold in evaporative mode, and expands absorbing heat from a stream of ambient air as it rises within the tubes and changing into a vapor phase. Momentum and gravity effects, due to the large mass differences between the liquid and gas phases of the refrigerant, can result in separation of the phases within the inlet manifold and cause poor refrigerant distribution throughout the core of the heat exchanger. Poor refrigerant distribution degrades evaporator performance and can result in uneven temperature distribution over the core.
Distributor tubes are known in the art to be used within inlet manifolds to aid in the even distribution of refrigerant through the core. Also, distributor tubes are known to be used in the outlet manifolds, the upper manifold in evaporative mode, to assist in the collection of refrigerant vapors to reduce the pressure drop through the core of the heat exchanger assemblies. A typical distributor tube includes a plurality of apertures axially spaced from one another for dispensing or receiving a refrigerant in a radial direction. The distributor tube is held in position as it extends through the inlet manifold by a braze joint on either ends of the manifold.
Audible noises are created due to the unconstrained increased length of the distributor tube swaying or vibrating resulting in repeated contact with the inside wall of the manifolds of a modified automotive heat exchanger assembly. Excessive continuous vibrations of the distributor tube may create fatigue fractures to the wall of the manifolds or to the distributor tube itself, as well as damaging the ends of the refrigerant tubes from repeated impacts of the distributor tube to the refrigerant tube ends. There exists a need to reduce the excessive vibrations of the distributor tube to reduce or eliminate audible noise and to prevent damage to the heat exchanger assembly.